Technical Field
The present invention relates to a toner, a developer, an image forming apparatus and a process cartridge.
Description of the Related Art
In recent years, toners have been required to have smaller particle diameters and hot offset resistance for increasing quality of output images, to have low-temperature fixability for energy saving, and to have heat resistant preservability for the toners to be resistant to high-temperature, high-humidity conditions during storage and transportation after production. In particular, improvement in low-temperature fixability is very important because power consumption in fixing occupies much of power consumption in an image forming step.
Conventionally, toners produced by the kneading pulverizing method have been used. In the toners produced by the kneading pulverizing method, is difficulty encountered in making them have smaller particle diameters, and their shapes are indefinite and their particle size distribution is broad, for which these toners have the following problems, for example: the quality of output images is not sufficient; and the fixing energy required is high. Also, when wax (release agent) has been added for improving fixability, the toners produced by the kneading pulverizing method are cracked at the interfaces with the wax upon pulverization, so that much of the wax is disadvantageously present on the toner surface. As a result, although releasing effects can be obtained, deposition (filming) of the toners on carriers, photoconductors, and blades will easily occur. Thus, their entire performances have not been satisfactory, which is problematic.
Then, in order to overcome the above problems accompanied by the kneading pulverizing method, toner production methods based on the polymerization method have been proposed. Toners produced by the polymerization method are easily allowed to have smaller particle diameters, and their particle size distribution is sharper than that of the toners produced by the pulverization method and moreover it is possible to enclose a release agent.